The present invention relates to an ultraviolet (hereinafter xe2x80x9cUVxe2x80x9d) light apparatus, module and system for the treatment of air which, upon exposure to UV light, will destroy harmful bacteria, micro-organisms and/or offensive and noxious odors in the air contained within a confined space or in air passing through a confined space such as a conduit or a heating/ventilation air conditioning (hereinafter xe2x80x9cHVACxe2x80x9d) duct.
UV light sources for the treatment of air typically take the form of a UV lamp positioned within a confined space such as the cross-sectional area of a conduit, for example, in a HVAC duct located in the home or an office building. UV lamps, such as those disclosed in U.S. Pat. No. 5,751,007 issued May 12, 1998, are known to emit UV light through two different types of tubing contained in the lamp, thereby generating UV light at different radiation wavelengths for destroying harmful bacteria and for the production of ozone to remove offensive and noxious odors. According to the disclosure of this patent, one kind of tubing will transmit light at wavelengths over the full radiation spectrum of UV light (what the patent refers to as UVA and UVB light), and the other tubing will transmit light at wavelengths only above 200 nanometers (defined in the patent as UVA light). The patent refers to UVA light as that light which is transmitted at wavelengths above 200 nanometers, and UVB light as that light which is transmitted at radiation wavelengths below 200 nanometers. However, according to a Microsoft Encarta Online Encyclopedia article entitled xe2x80x9cUltraviolet Lightxe2x80x9d by Thomas W. Davis, M.S., Ph.D. (published by the Microsoft Corporation, 2000), UV light is often divided into three different wavelength categories: UVA, UVB and UVC. In general, the shorter wavelengths of UV radiation are more dangerous to living organisms. Thus, UVA light has a wavelength from about 400 to about 315 nanometers; UVB light occurs at wavelengths from about 315 to about 280 nanometers, which causes sunburn and can cause skin cancer upon prolonged exposure; and UVC light has radiation wavelengths of approximately 290 to 15 nanometers which is often used to sterilize surfaces because of its germicidal activity against bacteria, viruses and micro-organisms. The xe2x80x9cOxford Dictionary Of Science,xe2x80x9d on the other hand, classifies ultraviolet light ranges according to its effects on the human skin, as UV-A (320-400 nm), UV-B (290-320), and UV-C (230-290 nm). And according to U.S. Pat. No. 4,967,090 issued Oct. 30, 1990, the U.S. FDA (Food and Drug Administration) defines UVA as the region of 320-400 nm and UVB as the region of 260-320 nm. In view of the foregoing discrepancies, and for the purposes of describing the invention herein, the term UVC shall refer to that ultraviolet light which occurs in the range of from about 15 to about 290 nanometers. Nonetheless, tubing consisting of special formula glass may be designed to be transparent to the longer UV wavelengths, while the use of pure quartz tubing is transparent to the entire, naturally occurring range of UV light, including ultraviolet ranges below 200 nm.
Within the UVC range of ultraviolet light as defined above, maximum germicidal activity is recognized to occur at a radiation wavelength of about 253.7 nanometers. As indicated above, germicidal activity alone (without the production of ozone) can be effected by the use of specially prepared quartz tubing for the UV lamp that is commonly referred to in the industry as L-quartz, which is quartz doped with titanium dioxide. However, when UVC light interacts with the oxygen in the ambient atmosphere at a radiation wavelength of approximately 185 nanometers, maximum ozone generation and output occurs. The production of ozone at this wavelength helps to reduce or substantially eliminate offensive and/or noxious odors that occur within the air, such as in air conditioning ducts in the home or office buildings when no fresh air is being introduced into the system. This condition generally occurs when air is being constantly re-circulated through a HVAC system under circumstances when minimal amounts of fresh air are introduced into the system, typically during cold weather conditions in order to conserve heat and reduce energy consumption.
As indicated above, ozone production from a UV lamp can be effected by the use of high quality clear quartz tubing, available and referred to in the industry as VH-quartz, which allows the transmission of UV light at both the 185 and 253.7 nanometer radiation wavelengths. Therefore, by employing a UV lamp having both these types of tubing, in combination with an adjustable sleeve covering a portion of the VH-quartz tubing for blocking or absorbing the transmission of ultraviolet light that will produce ozone, such as that described in U.S. Pat. No. 5,751,007, one can purify and/or treat the air and simultaneously control the production of ozone for eliminating offensive and/or noxious odors.
Unfortunately, the control of the rate of ozone emitted in a HVAC duct by a system that employs the UV lamp apparatus described in U.S. Pat. No. 5,751,007, is hampered by the duct system that conveys the conditioned air, either because of the inaccessibility of the UV lamp itself, or because of the necessity of having to shut down the UV air disinfection system to manually adjust the sleeve which, in this patent, is mounted directly to the lamp""s tubing. It is therefore important and desirable to monitor the levels of ozone and provide for the manual and/or automatic adjustment of the sleeve from a location exterior and/or remote from the duct system, without having to shut down the operation of the UV air disinfection system. Discontinuing operation of the system to either change the lamp or to manually adjust the sleeve""s position for controlling the UV lamp""s ozone output also leads to an inefficient operation. Furthermore, it should be kept in mind that while the formation of ozone within the duct is desirable for reducing and/or eliminating noxious odors, the ozone produced should not reach levels where it becomes toxic to the persons being exposed to it, since prolonged exposure to elevated levels of ozone can be harmful.
In order to overcome the foregoing difficulties, the present invention provides an ultraviolet light apparatus, module and system for the treatment of air within a confined structure, such as a HVAC duct, to disinfect the air therein, and for controlling the amount of ozone generated by the ultraviolet light apparatus for substantially reducing and/or eliminating offensive and/or noxious odors carried by the air within the confined structure.
The ultraviolet light apparatus comprises an ultraviolet light-emitting lamp that includes at least one composite tubing which comprises (a) a first section for transmitting ultraviolet light in a wavelength range that includes maximum ozone production and maximum germicidal activity; and (b) a second section for transmitting ultraviolet light in a wavelength range that includes maximum germicidal activity and excludes the production of ozone. The ultraviolet light apparatus also includes (c) a movable annular sleeve whose annulus completely surrounds a portion of the composite tubing of the ultraviolet light-emitting lamp in a frictionless manner. The sleeve is capable of blocking ultraviolet light in a wavelength range that produces ozone while simultaneously allowing the transmission of ultraviolet light at a wavelength range that produces germicidal activity.
The ultraviolet light-emitting lamp may be configured as comprising a straight composite tubing, or it may comprise two, substantially parallel, tubularly connected segments, the first section of the composite tubing forming a portion of at least one of the segments. This includes a UV lamp having a generally C-shaped configuration whose opposite ends terminate in a common lamp base.
The annular sleeve is such that it is capable of blocking ultraviolet light in a wavelength range that produces ozone while simultaneously allowing the transmission of ultraviolet light in a wavelength range that produces germicidal activity. In order to accomplish this, the sleeve is preferably constructed of specially prepared fused quartz (known in the industry as xe2x80x9cL-quartzxe2x80x9d) or transparent Teflon(copyright). The annular sleeve is preferably of sufficient length to completely surround the first section of the composite tubing of the ultraviolet light-emitting lamp.
Alternatively, the entire tubing of the ultraviolet light-emitting lamp may be such that it will transmit ultraviolet light in a wavelength range that includes maximum ozone production and maximum germicidal activity, and includes tubing that has a straight length as well as two, substantially parallel, tubularly connected segments as described above. In either case, the opening of the sleeve combined with the sleeve""s length, is configured such that it will completely surround the entire tubing of the ultraviolet light-emitting lamp. The annular sleeve has the same characteristics as the sleeve described above for the UV lamp comprising the composite tubing.
The invention also extends to the utilization of the ultraviolet light apparatus in modular form for operation of the annular sleeve to control the amount of ozone transmitted by the ultraviolet light-emitting apparatus to a confined space, e.g., a conduit having the passage of air flowing therethrough. Therefore, in addition to the ultraviolet light apparatus, the ultraviolet light module comprises a drive mechanism for the frictionless displacement of the annular sleeve along the longitudinal axis of the ultraviolet light apparatus"" composite tubing for controlling the amount of ozone transmitted by the same.
In one aspect of the invention, the drive mechanism comprises an elongate threaded rod engaged at one end portion thereof with a means for rotating the rod, preferably an electric motor, with the opposite end portion of the rod being operatively engaged with a correspondingly threaded opening within a retainer member mounted to or fixed to the annular sleeve. When the threaded rod is rotated by, for example, an electric motor, or manually by the employment of a handle on the end portion of the threaded rod, the annular sleeve will be displaced along the longitudinal axis of the composite tubing of the ultraviolet light-emitting lamp. A guide rod may optionally be detachably fixed to the conduit to which the module is incorporated with, such that the guide rod communicates with a slidable stabilizer member fixed to the retainer member, the guide rod being in parallel relationship with the threaded rod to prevent the transmission of torsional forces to the annular sleeve by the rotation of the threaded rod.
Alternatively, and in keeping with another aspect of the invention, the drive mechanism may comprise a pneumatically or hydraulically operated piston secured about one end of an elongate rod, with the retainer member being secured about the opposite end of the elongate rod for the displacement of annular sleeve along the longitudinal axis of the composite tubing of the lamp when the piston is activated.
In yet another aspect of the invention, the ultraviolet light module may additionally comprise a housing for the drive mechanism, preferably configured so that the housing, ultraviolet light apparatus, and drive mechanism form a single unit. The housing, in turn, may also include a ballast for powering the ultraviolet light apparatus as well as a socket means mounted to or integral with the housing for receiving the ultraviolet lamp. A switch means may optionally be included with the housing for automatically disconnecting electrical power to the ultraviolet light-emitting lamp and/or drive mechanism when the housing is separated from the confined space, e.g., a conduit for the passage of air therethrough to which the ultraviolet light module is incorporated. In addition, the housing may also include an electrically activated, audible and/or visual alarm when the ultraviolet light-emitting lamp, ballast or drive mechanism ceases to function.
As an ultraviolet light air treatment system, the housing, ultraviolet light apparatus and drive mechanism are configured to form a single unit for incorporation with a conduit for treating the air passing therethrough.